The purpose of this study is to identify the genes predisposing to Hirschsprung Disease (HSCR) and to clarify the genetic heterogeneity. A comprehensive family history study and segregation analysis is on-going to definitely establish the mode(s) of inheritance of HSCR. Concurrently, cytogenetic studies will be conducted to identify possible chromosome aberrations. Further linkage studies will be performed, using candidate genes and regions, to map the genes involved in HSCR. The general objective of this study is to provide a logical framework for identifying the genes involved in a complex, "multifactorial" disease.